001/**
002 *
003 * Copyright 2017 Florian Schmaus
004 *
005 * Licensed under the Apache License, Version 2.0 (the "License");
006 * you may not use this file except in compliance with the License.
007 * You may obtain a copy of the License at
008 *
009 *     http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.jivesoftware.smackx.eme.element;
018
019import java.util.HashMap;
020import java.util.Map;
021
022import org.jivesoftware.smack.packet.ExtensionElement;
023import org.jivesoftware.smack.packet.Message;
024import org.jivesoftware.smack.util.StringUtils;
025import org.jivesoftware.smack.util.XmlStringBuilder;
026
027public class ExplicitMessageEncryptionElement implements ExtensionElement {
028
029    private static final Map<String, ExplicitMessageEncryptionProtocol> PROTOCOL_LUT = new HashMap<>();
030
031    public static final String ELEMENT = "encryption";
032
033    public static final String NAMESPACE = "urn:xmpp:eme:0";
034
035    public enum ExplicitMessageEncryptionProtocol {
036
037        /**
038         * The encryption method specified in <a href="https://xmpp.org/extensions/xep-0373.html">XEP-0373: OpenPGP for
039         * XMPP</a>.
040         */
041        openpgpV0("urn:xmpp:openpgp:0", "OpenPGP for XMPP (XEP-0373)"),
042
043        otrV0("urn:xmpp:otr:0", "Off-the-Record Messaging (XEP-0364)"),
044
045        legacyOpenPGP("jabber:x:encrypted", "Legacy OpenPGP for XMPP [DANGEROUS, DO NOT USE!]"),
046        ;
047
048        private final String namespace;
049        private final String name;
050
051        ExplicitMessageEncryptionProtocol(String namespace, String name) {
052            this.namespace = namespace;
053            this.name = name;
054            PROTOCOL_LUT.put(namespace, this);
055        }
056
057        public String getNamespace() {
058            return namespace;
059        }
060
061        public String getName() {
062            return name;
063        }
064
065        public static ExplicitMessageEncryptionProtocol from(String namespace) {
066            return PROTOCOL_LUT.get(namespace);
067        }
068    }
069
070    private final String encryptionNamespace;
071
072    private final String name;
073
074    private boolean isUnknownProtocol;
075
076    private ExplicitMessageEncryptionProtocol protocolCache;
077
078    public ExplicitMessageEncryptionElement(ExplicitMessageEncryptionProtocol protocol) {
079        this(protocol.getNamespace(), protocol.getName());
080    }
081
082    public ExplicitMessageEncryptionElement(String encryptionNamespace) {
083        this(encryptionNamespace, null);
084    }
085
086    public ExplicitMessageEncryptionElement(String encryptionNamespace, String name) {
087        this.encryptionNamespace = StringUtils.requireNotNullOrEmpty(encryptionNamespace,
088                        "encryptionNamespace must not be null");
089        this.name = name;
090    }
091
092    public ExplicitMessageEncryptionProtocol getProtocol() {
093        if (protocolCache != null) {
094            return protocolCache;
095        }
096
097        if (isUnknownProtocol) {
098            return null;
099        }
100
101        ExplicitMessageEncryptionProtocol protocol = PROTOCOL_LUT.get(encryptionNamespace);
102        if (protocol == null) {
103            isUnknownProtocol = true;
104            return null;
105        }
106
107        protocolCache = protocol;
108        return protocol;
109    }
110
111    public String getEncryptionNamespace() {
112        return encryptionNamespace;
113    }
114
115    /**
116     * Get the optional name of the encryption method.
117     *
118     * @return the name of the encryption method or <code>null</code>.
119     */
120    public String getName() {
121        return name;
122    }
123
124    @Override
125    public String getElementName() {
126        return ELEMENT;
127    }
128
129    @Override
130    public String getNamespace() {
131        return NAMESPACE;
132    }
133
134    @Override
135    public XmlStringBuilder toXML() {
136        XmlStringBuilder xml = new XmlStringBuilder(this);
137        xml.attribute("namespace", getEncryptionNamespace());
138        xml.optAttribute("name", getName());
139        xml.closeEmptyElement();
140        return xml;
141    }
142
143    public static ExplicitMessageEncryptionElement from(Message message) {
144        return message.getExtension(ELEMENT, NAMESPACE);
145    }
146}